The Internet has emerged as a critical communication infrastructure, carrying traffic for a wide range of important applications. Internet services such as VoIP and SoIP services are becoming ubiquitous and businesses and consumers are relying on their Internet connections to obtain many of their communications services. However, the Internet is a public network and is not as reliable or secure as privately leased lines. The privately leased lines are not shared, and provide predetermined performance level and security. However, as businesses expand globally, the number of interconnected sites increases. The cost of enabling all employees and business partners to communicate via leased lines is prohibitive. Network service providers offer Virtual Private Network (VPN) services to enterprises with a need to communicate across multiple geographical areas. That is, the enterprise customers extend their network by establishing a wide area network using the VPN services offered by a network service provider. An enterprise customer may obtain multiple VPN services. The network service providers have multiple Border Gateway Protocol (BGP) autonomous systems to support their large customer base. Multiple VPNs for a customer may be provided on autonomous systems within the same Interior Gateway Protocol (IGP) or on multiple BGPs. When a customer requests multiple VPNs to be combined, e.g., due to mergers of network service providers, an inter-autonomous-system with complex BGP topology, route reflectors, route filter list, etc. is used. If the number of VPNs being combined is significantly large, then the filter lists will in turn become very large and very difficult to manage. Route reflectors may be required to handle a larger load, thereby affecting the performance of the overall network.
Therefore, there is a need for a method that provides communication for VPNs spanning multiple autonomous systems.